The specific emissions of air pollutants from passenger and freight
transport decreased during the time period 1995-2009 for the majority of
transport modes and especially for passenger transport. The highest reduction
of specific emissions can be observed in the road sector, following the implementation
of increasingly strict emission standards. Railway and aviation have also
recorded reductions, while maritime passenger and freight transport emissions
remained approximately constant over the same time period. Rail and water
transport are still relatively clean forms of transport - compared to road and
air transport - but without any regulations on their emissions, these modes might
lose this leading position.

Key messages

The specific emissions of air pollutants from passenger and freight
transport decreased during the time period 1995-2009 for the majority of
transport modes and especially for passenger transport.

The highest reduction
of specific emissions can be observed in the road sector, following the implementation
of increasingly strict emission standards.

Railway and aviation have also
recorded reductions, while maritime passenger and freight transport emissions
remained approximately constant over the same time period.

Rail and water
transport are still relatively clean forms of transport - compared to road and
air transport - but without any regulations on their emissions, these modes might
lose this leading position.

Is the reduction in specific emissions consistent with the stricter emission standards?

Specific emissions of VOC per passenger-km or tonne-km and per mode of transport, 1995-2009

Road
remains by far the most polluting passenger transport mode with respect to CO
and VOC specific emissions, even though it recorded the highest decreases
(about 85 % for both CO and VOC emissions) from 1995 to 2009 compared to the
other modes. As regards NOx and PM specific emissions, road
passenger transport specific emissions are comparable with those of air and
rail transport. Road is also the most polluting freight transport mode for all
pollutants (with the exception of PM), although the specific emissions
decreased from 42 % (NOx) to 72 % (PM) over the 1995 to 2009 period.

Rail
is generally the cleanest mode of transport for most pollutants. Specific NOx
and PM emissions of rail transport have decreased considerably from 1995 to
2009, mainly due to the trend towards electric powered trains, especially for
passenger traffic. Specific emissions from trains depend critically on the
technical level and the method of energy production used. The emission factors
for electricity production represent the airborne pollutants incurred during
the whole production and supply process from fuel extraction to electricity
transport to the sub-stations feeding the railway network. This indicates that
the focus in the future should be in controlling emissions from power
generation, along with implementing the engine economy and emission control
technology, which has already advanced.

Maritime
shipping is one of the cleanest mode of freight transport, except for PM and
specific sulphur oxide (SOx) emissions, which are the highest for
shipping (and aviation), mainly due to the high sulphur content of bunker
fuels. However, maritime shipping remains by far the most polluting passenger
transport mode with regard to the specific NOx and PM emissions. The
emissions generated by the maritime fleet are largely dependent on the quantity
of fuel consumed; however, there are several factors besides fuel consumption,
which influence the emissions generated. These include the fuel quality and the
engine type. In particular, SOx and PM emissions are influenced by
the quantity of sulphur within the fuel. In the future, emission reductions are
expected from waterborne transport, mainly as a result of improved fuel quality
and engine technology. EU legislation (Directive 2005/33/EC) setting more
stringent limits for sulphur content in fuel oils will greatly contribute to
the expected emission reductions. In addition to this, Commission
Recommendation 2006/339/EC aims at promoting of shore-side electricity for use
by ships at berth in Community ports.

Specific
emissions of CO and VOC from aviation are generally low, being comparable to
those of maritime shipping. The International
Civil Aviation Organization (ICAO) has established aircraft engine emission
standards for NOx, which resulted in 30 % reductions achieved from 1995 to 2009. Despite this reduction,
NOx specific emissions are still 40 to 60 % higher compared to road and
rail respectively.

It
should be noted that the significant reductions in the emissions of all
pollutants from road transport are mainly attributed to technological
improvements and policy measures resulting from the strict emission standards
imposed. On the other hand, the emissions from the other modes of transport are
not subject to any emission control regulations, which would result in emission
reductions similar to those from road transport.

Indicator specification and metadata

Indicator definition

Specific emissions are defined as emissions of pollutants per transport unit (passenger-km or tonne-km), specified by mode (road, rail, inland, maritime, air). The pollutants considered include NOx, VOC, PM and CO.

Rationale

Justification for indicator selection

Transport is a major contributor to air pollution. In 2010, road transport alone accounts for 42, 16, 15 and 29 % of total NOx, VOC, PM and CO emissions respectively (see TERM 03 - Transport emissions of air pollutants). Advanced after-treatment technology introduced by the automobile industry due to tighter emission limits can therefore result in considerable reduction in specific pollutant emissions.

The specific emissions of air pollutants of passenger and freight transport are determined by the fleet composition (number and type of vehicles), vehicle utilisation (occupancy rates and load factors) and driving characteristics (speeds, distances). This indicator has been selected to monitor the impact of the stricter emission standards on the specific emissions of air pollutants of the various passenger and freight transport modes.

Scientific references

No rationale references
available

Policy context and targets

Context description

Since specific
emissions are expressed per transport unit, occupancy rates and load factors
have a considerable effect on specific emissions produced from passenger and
freight transport respectively. Reduction of specific emissions can be achieved
by increasing occupancy rates and load factors and/or by decreasing the
emissions per vehicle-km (e.g. by setting stricter emission standards and
introducing more energy efficient technologies such as hybrid, plug-in hybrids,
electric vehicles, etc).

Targets

No explicit targets exist at European level directly addressing specific emissions. Policy objectives are rather set with respect to the environmental performance of the fleet (see also TERM 34).

Related policy documents

No related policy documents have been specified

Methodology

Methodology for indicator calculation

For passenger transport, the specific emissions are calculated by dividing the pollutant emissions of each mode (i.e. road, rail, maritime and air transport) by the respective passenger-kilometres. For freight transport, the specific emissions are calculated by dividing the pollutant emissions of each mode (i.e. road, rail, inland shipping and maritime transport) by the respective tonne-kilometres.

The pollutant emissions for the remaining modes of transport (i.e. rail, inland shipping, maritime and air transport) are calculated using Tier 1 emission factors from the EMEP/EEA air pollutant emission inventory guidebook.

For air transport, the number of total LTOs (from EUROSTAT-avia_tf_aca) is used to calculate the pollutant emissions.

For the calculation of emissions from electric trains, the relevant emission factor from electricity generation (in grams of pollutant per kWh of energy produced) was used. To this aim, the total emissions of each pollutant (data from the EU submission to CLRTAP), were divided by the total electricity production in the European Union (data from EUROSTAT).

Methodology for gap filling

Passenger- and tonne-kilometres and emissions of NOx, VOC, PM and CO are modelled and therefore no gap filling is necessary.

Methodology references

Uncertainties

Methodology uncertainty

COPERT 4 is used for road transport emissions calculations in EC4MACS, whereas the Tier 1 method of the EMEP/EEA air pollutant emission inventory guidebook is used for non-road transport modes.

Data sets uncertainty

Since the data on pollutant emissions, passenger-km and tonne-km are modelled rather than measured, the data must be treated as estimates. The uncertainty of emissions and the uncertainty of passenger-km and tonne-km vary significantly among different countries depending on the underlying statistical data used for each country